From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: [PATCH v6 09/10] xen/arm: Set foreign page type to p2m_map_foreign Date: Tue, 17 Dec 2013 16:27:57 +0000 Message-ID: <1387297678-17762-10-git-send-email-julien.grall@linaro.org> References: <1387297678-17762-1-git-send-email-julien.grall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VsxVx-00068U-9g for xen-devel@lists.xenproject.org; Tue, 17 Dec 2013 16:28:57 +0000 Received: by mail-ee0-f42.google.com with SMTP id e53so2964587eek.15 for ; Tue, 17 Dec 2013 08:28:55 -0800 (PST) In-Reply-To: <1387297678-17762-1-git-send-email-julien.grall@linaro.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xenproject.org Cc: Julien Grall , ian.jackson@eu.citrix.com, ian.campbell@citrix.com, patches@linaro.org List-Id: xen-devel@lists.xenproject.org Xen needs to know that the current page belongs to another domain. Also take a reference to this page. The current process to add a foreign page is: 1) get the page from the foreign p2m 2) take a reference on the page with the foreign domain in parameters 3) add the page to the current domain p2m If the foreign domain drops the page: - before 2), get_page will return NULL because the page doesn't belong anymore to the domain - after 2), the current domain already have a reference. Write will occur to an old page which is not yet released. It can corrupt the foreign domain. Signed-off-by: Julien Grall Acked-by: Ian Campbell --- Changes in v5: - Missing rcu_unlock_domain in one path - Check if the foreign page is RAM Changes in v4: - Typo s/release/released/ - Improve commit message Changes in v3: - Typoes - Check if the foreign domain is different from the current domain Changes in v2: - Even if gcc is buggy (see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18501) define p2m type per mapspace to let the compiler warns about unitialized values. --- xen/arch/arm/mm.c | 38 ++++++++++++++++++++++++++++++-------- xen/include/asm-arm/p2m.h | 1 + 2 files changed, 31 insertions(+), 8 deletions(-) diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index b1222be..6829822 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c @@ -977,6 +977,7 @@ static int xenmem_add_to_physmap_one( { unsigned long mfn = 0; int rc; + p2m_type_t t; switch ( space ) { @@ -1009,22 +1010,33 @@ static int xenmem_add_to_physmap_one( d->arch.grant_table_gpfn[idx] = gpfn; + t = p2m_ram_rw; + spin_unlock(&d->grant_table->lock); break; case XENMAPSPACE_shared_info: - if ( idx == 0 ) - mfn = virt_to_mfn(d->shared_info); - else + if ( idx != 0 ) return -EINVAL; + + mfn = virt_to_mfn(d->shared_info); + t = p2m_ram_rw; + break; case XENMAPSPACE_gmfn_foreign: { - paddr_t maddr; struct domain *od; + struct page_info *page; + p2m_type_t p2mt; od = rcu_lock_domain_by_any_id(foreign_domid); if ( od == NULL ) return -ESRCH; + if ( od == d ) + { + rcu_unlock_domain(od); + return -EINVAL; + } + rc = xsm_map_gmfn_foreign(XSM_TARGET, d, od); if ( rc ) { @@ -1032,15 +1044,25 @@ static int xenmem_add_to_physmap_one( return rc; } - maddr = p2m_lookup(od, pfn_to_paddr(idx), NULL); - if ( maddr == INVALID_PADDR ) + /* Take reference to the foreign domain page. + * Reference will be released in XENMEM_remove_from_physmap */ + page = get_page_from_gfn(od, idx, &p2mt, P2M_ALLOC); + if ( !page ) { dump_p2m_lookup(od, pfn_to_paddr(idx)); rcu_unlock_domain(od); return -EINVAL; } - mfn = maddr >> PAGE_SHIFT; + if ( !p2m_is_ram(p2mt) ) + { + put_page(page); + rcu_unlock_domain(od); + return -EINVAL; + } + + mfn = page_to_mfn(page); + t = p2m_map_foreign; rcu_unlock_domain(od); break; @@ -1051,7 +1073,7 @@ static int xenmem_add_to_physmap_one( } /* Map at new location. */ - rc = guest_physmap_add_page(d, gpfn, mfn, 0); + rc = guest_physmap_add_entry(d, gpfn, mfn, 0, t); return rc; } diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h index 8b7b6d0..53b3266 100644 --- a/xen/include/asm-arm/p2m.h +++ b/xen/include/asm-arm/p2m.h @@ -47,6 +47,7 @@ typedef enum { } p2m_type_t; #define p2m_is_foreign(_t) ((_t) == p2m_map_foreign) +#define p2m_is_ram(_t) ((_t) == p2m_ram_rw || (_t) == p2m_ram_ro) /* Initialise vmid allocator */ void p2m_vmid_allocator_init(void); -- 1.7.10.4